1. Field of the Invention
This invention relates to packaging and more particularly to a packaging device for lighting modules such as those used for illuminating channel letters.
2. Background of the Invention
Light emitting diodes (LED or LEDs) are solid state devices that convert electric energy to light, and generally comprise one or more active layers of semiconductor material sandwiched between oppositely doped layers. When a bias is applied across the doped layers, holes and electrons are injected into the active layer where they recombine to generate light. Light is emitted from the active layer and from all surfaces of the LED.
Developments in LED technology have resulted in devices that are brighter, more efficient and more reliable. LEDs are now being used in many applications that were previously the realm of incandescent fluorescent or neon bulbs; some of these include displays, automobile taillights and traffic signals. LEDs are also now being used to illuminate channel letter signs. These lighting systems typically comprise a plurality of LED modules each of which has at least one LED. These modules are interconnected by wires that transmit an electrical signal between the modules such that an electrical signal applied to the input end of the modules is transmitted to all the interconnected modules. One example of these interconnected LED modules is described in U.S. Pat. No. 6,932,495 to Sloan et al. (assigned to the assignee as the present application) entitled “Channel letter lighting using light emitting diodes.” The desired length of interconnected LED modules can typically be cut from the remainder, with the LED modules in both the cut portion and remainder capable of emitting light by applying an electrical signal.
Interconnected LED modules are typically provided to the consumer in various packages which can be disorganized and inconvenient. Two examples of these include bags and boxes with the LED modules and wires loosely arranged therein. These packages can lead to tangling and related difficulties in removing the LED modules in an orderly way. It is also difficult to determine what length of LED module is provided in or remains in the packaging, and it is also difficult to determine the appropriate location to cut the interconnected modules when a shorter length is desired. It can also be difficult to see all of the modules during visual inspection and illumination testing.
U.S. Pat. No. 6,846,093 to Swaris et al. discloses another package for interconnected LED modules with the package comprising a dispensing roll having pre-wired LED modules wound upon a roller. In use the desired length of the modules are pulled from the dispenser to progressively install the pre-wired LED modules. When the appropriate number of LED modules are installed, the worker simply snips the wires disconnecting the installed LED modules from the LED modules that are still on the dispensing roll. With this arrangement, however, it is difficult to determine the length of modules on the role and a significant number of modules can be hidden below other modules on the roll making it difficult to visually and electrically test the modules. Further, the desired length of modules must first be unwound from the roll before being cut. There is no mechanism for determining the proper cutting location while the modules are still on the roll.